A conventional method of producing in automatic highspeed mode a slide fastener with a separator consists in the main of:
(1) producing a pair of stringers by attaching by sewing to a pair of tapes placed side by side along the opposing inner edge of each, interlocking coil coupling elements of synthetic resin monofilament;
(2) producinga continuous synthetic resin slide fastener chain by removing a predetermined length of the coupling elements from the stringers at a predetermined intervals so as to form spaced sections or element-free sections thereon;
(3) producing a plain slide fastener chain by the cutting of such a continuous synthetic resin slide fastener chain at spaced sections; and,
(4) completing as a product the slide fastener by furnishing this plain slide fastener chain at its ends with a top stop and a separator composed of pin, or male member, box, and box pin or female member respectively, and a slider for free vertical movement along the coupling elements.
Japanese Opened Patent Application No. 156104/81, filed by this applicant, disclosed the method of forming an element-free section or spaced section in a continuous slide fastener chain, in a manner as illustrated by above step (2). According to this patent application, a punch with a single cutting edge of length related with the longitudinal dimension of the segment-free section cuts the loops or winds of the right and left coil coupling elements, as they are interlocked in stringers, on the inner sides each of the threads that fix them to the tapes. At the subsequent stage, to form the spaced section, the severed coil element fragments are extracted by plucking them adjacent to the cut ends between the threads. However, this process has certain disadvantages. For example, the coil element fragments offer a considerable resistance against pull since they are tightly entwined with the threads. As a result, fragments remain unremoved in the threads or, in an extreme case, break the thread. Further, cutting in this manner would leave the coil elements with free bent ends where cut which extend too far out from the sewing threads into the spaced section thus formed. When a top stop is attached to the stringer on this side, these cut ends can be left protruding from the top stop. Consequently, the user, when wearing clothing or the like to which this coil element slide fastener is attached, will come into contact with, and be hurt by, the protruding coil ends, so that the fastener has a disagreeable touch and feel.
An improved approach for overcoming the above mentioned disadvantages has been made by this applicant, which is disclosed in Japanese Utility Model Application No. 197537/81. According to this, a punch with two cutting edges, spaced in parallel and of a length equal to the dimension of the spaced section, cuts the loops or winds of the coil elements on the external or outer side of either sewing thread. Punching is followed by extraction of the severed coil element fragments, which are plucked between the threads. Extraction occurs with the element fragments being crushed enough to be freed of the binding force of the sewing threads enabling eased removal without causing breakage in the threads. In addition, excessively long cut ends on the stringer coil elements are no longer left free on that end where the top stop, according to the aforesaid patent application, would have objectionable and possibly harmful projections. On the other hand, however, this utility model application is disadvantageous in that excessively long cut ends are left free on the other end of the stringer coil elements. When attaching such fittings as a box pin, pin and box for a separator to this end of the stringer coil elements, it is very difficult to make these ends stay in the box pin or pin. Consequently, the user has a protruding coil end on clothing to which this slide fastener is attached, which he will come into contact with and which may hurt him. In addition, this leads to so called "chain splitting" when used for a long time.